The polyphenylene sulfide resin (hereinafter abbreviated as PPS resin) has the rigidity, the heat resistance, the hot water resistance, the chemical resistance and the molding processability in a good balance and is thus widely used for various applications. In recent years, the PPS resin is used for plumbing components and automobile applications, based on the above characteristics. The PPS resin, however, generally tends to have the lower toughness expressed by the tensile fracture elongation and the impact strength, compared with the other engineering plastics. The improvement in toughness is accordingly an important issue.
In order to solve this issue, methods of producing the PPS resin compositions by mixing various elastomers with the PPS resin have been proposed. For example, Patent Document 1 shows a method of mixing an ethylene-α-olefin elastomer having the excellent toughness. Addition of the ethylene-α-olefin elastomer to the PPS resin improves the toughness but, on the other hand, deteriorates the molding processability. In other words, mixing the ethylene-α-olefin elastomer with the PPS resin reveals the problem of increasing the gas emission and the mold deposit (mold stain) during molding and the problem of deforming a molded product in the course of mold release from a mold (deteriorating the mold releasability). This is because the PPS resin has the molding temperature of as high as 280° C. or higher and part of the ethylene-α-olefin elastomer is thermally decomposed in the process of producing a molded product. This results in increasing the gas emission during molding to cause clogging of a mold vent, deteriorating the appearance of a molded product by the mold deposit and increasing the tackiness of the surface of a molded product.
Various techniques have also been employed to reduce the gas emission and the mold deposit with respect to this PPS resin composition. For example, in order to achieve improvement in molding processability, one technique changes the elastomer to be mixed with the PPS resin to an α-olefin elastomer having high heat resistance. Another technique adds an adsorbent to trap the emitted gas. Yet another technique enforces degassing in the course of melt kneading the PPS resin with an elastomer. These techniques, however, do not sufficiently improve the mold releasability.
Patent Document 2, on the other hand, describes the configuration of using a carboxylic acid amide wax, which is obtained by the reaction of a higher aliphatic monocarboxylic acid, a polybasic acid and a diamine of the component (C), as a mold release agent. The cause of the mold deposit is, however, not limited to the ethylene-α-olefin elastomer, but generation of the degradation products of the mold release agent is also one of the major causes. The above technique alone can thus not sufficiently reduce the mold deposit. A possible measure of reducing the mold deposit is changing the above mold release agent to another mold release agent having little generation of the degradation products, which may provide the cause of mold deposit. Changing the mold release agent, however, often deteriorates the mold releasability, even when reducing the mold deposit. It is accordingly difficult to satisfy both the good mold releasability and the reduced mold deposit.